Field of the Invention
The present invention relates to an imprint apparatus for bringing a mold having a pattern region in which a pattern is formed into contact with an imprint material on a substrate and transferring the pattern to the imprint material, and a method of manufacturing an article by using the apparatus.
Description of the Related Art
Recently, as demands for micropatterning semiconductor devices increase, an imprint technique of transferring a fine pattern formed on a mold to an imprint material on a substrate is attracting attention, in addition to the conventional photolithography technique. This imprint technique is useful in the formation of nanoscale patterns, and also called a nanoimprint technique. An example of the imprint technique is a method using an optical imprint system in the semiconductor manufacturing technique as disclosed in Japanese Patent Laid-Open No. 2005-286062. In this method, a resin as one of examples of an imprint material is dispensed on a substrate such as a semiconductor wafer, a mold having a desired fine three-dimensional structure is pressed against the resin, and the resin is cured by irradiation with ultraviolet light in this state. Consequently, the three-dimensional structure of the mold is transferred to the resin. A layer below the resin can be processed by etching the layer by using the resin as an etching mask. An imprint apparatus does not require any projecting optical system or the like, and hence is superior in space saving and cost to a photolithography type semiconductor exposure apparatus. Also, Japanese Patent Laid-Open No. 2009-517882 describes a technique by which the mold is deformed into a projecting shape, the central portion and its vicinity of the mold are first brought into contact with the resin on the substrate, and then the contact region is gradually extended from the central portion to the peripheral portion, in order to shorten the time required to fill the resin in recesses of the mold, and reduce the force required to release the mold from the resin.
In the imprint apparatus, the mold and substrate are physically brought into contact with each other with the resin being sandwiched between them. Therefore, a force is applied to the substrate when the mold is brought into contact with the substrate and released from the cured resin, and the substrate sometimes moves from the original position. If an imprint (pattern transfer) operation is performed on the next shot region with the substrate being kept moved from the original position, an overlay error may occur. Accordingly, demands have arisen for so-called, die-by-die alignment by which the substrate and mold are aligned for each shot region.
The imprint apparatus can adopt a through the mold detecting system (to be referred to as a TTM detecting system hereinafter) capable of directly aligning the mold and substrate. In the imprint apparatus, an irradiation system is positioned above the mold so as to irradiate the resin with ultraviolet light through the mold, and the TTM detecting system is positioned to get out of the way of the irradiation system.
The vicinity of the irradiation system positioned above the mold is a crowded place because various parts such as an imprint head for holding the mold and a driving cable connected to the head are arranged. Therefore, the TTM detecting system must be positioned to avoid interference with the irradiation system and a light beam for curing, and hence is conventionally inclined to the optical axis of the irradiation system. Also, alignment marks are arranged in the peripheral portion of a region to be irradiated with the curing light.
On the other hand, when the mold is deformed and the vicinity of its central portion is first brought into contact with the substrate, if alignment marks are arranged in the peripheral portion of the mold, the alignment operation must wait until the peripheral portion comes in contact with the resin.